The innovation engine for new materials

Rory Barker

Rory Barker


University of Oxford, UKk


Department of Materials


Christine Link

Faculty Sponsor(s): 

Ram Seshadri

Faculty Sponsor's Department: 

Materials Research Laboratory

Project Title: 

Forming a Tunable Phosphor by the Solid Solution of Ca2MgSi2O7 and Ca2ZnSi2O7 Doped with Europium

Project Description: 

Modern solid-state white lighting using phosphor-converted LEDs is a more efficient, more robust, and longer lasting alternative to all other white light sources currently used. However, most solid-state white lighting lacks light in the red spectral region (~600 nm), which results in poor colour rendering. For solid-state white lighting to be widely used, the colour rendering must be improved by developing high efficiency red phosphors. Ca1.975Eu0.025MgSi2O7 is an efficient green phosphor, with peak emission around 518 nm; Ca1.975Eu0.025ZnSi2O7 is a less efficient red phosphor with peak emission around 602 nm. The aim is to produce a tunable phosphor with a peak emission that can be shifted between 518 and 602nm by varying composition of Ca2Mg1-xZnxSi2O7. These phosphors are produced by firing at temperatures between 1200-1250 °C in a reducing atmosphere while reagents remain in the solid state. Absorption and emission spectra are characterised by fluorometry, and quantum yield is measured using an integrating sphere. Preparation of the phosphors proves difficult since ZnO easily reduces to Zn metal, which evaporates at 900 °C, however this is potentially being overcome by the use of excess ZnO in the reaction, and capping the reaction vessel